6 Replies Latest reply on Feb 23, 2015 7:19 PM by Jared Conway

    Overlapping Shell Elements?

    Chris Ross

      I have a weldment that I'm working on analyzing.  It is primarily angles and plate.  There are several areas where the plates overlap the legs of the angles.  I then created midplane shell elements and suppressed all the solids.  What is the best way to connect the plates to the shells where they overlap since there is now a gap between the parallel shell elements?  I've tried doing split lines on the both the plate and the angle and then creating a bonded contacted between the edges that would be where the welds would be.  The bonded contacts seem to be inconsistent.  Some shells will stay bonded, others just fly apart even though I've applied a bonded contact to the edges.

        • Re: Overlapping Shell Elements?
          Jared Conway

          could you post some pictures? are the "angles" solids or shells or beams

           

          why do parts overlap? and do you mean that they are coincident or that they interfere?

           

          generally if the parts are coincident in your model and you idealize them, the contacts are applied automatically so eventhough there is "theoretically" a gap, there really isn't

            • Re: Overlapping Shell Elements?
              Chris Ross

              I can't attach the model I'm working on due to confidentiality, but here is a model that is representative of the problem.  The first simulation shows the default.  Even though the thickness of each part puts them in contact, Solidworks does not automatically bond them together.  I had to turn soft springs and inertial relief on just to get it to run and you can see the angle is detached.  The second simulation has the edges bonded.  This works on this particular model, but I'm using this technique on my model and some of the joints work with this and other joints fly apart.  Can't seem to figure out any reason why this works on some joints and not on others.  The third setup uses welded joints.  This seems to work also in this model, but in my model, some joints it allows me to apply this to, others joints it gives me an error saying they aren't parallel, yet they are.  Very frustrated with the lack of consistency in how these joints work in simulation.

                • Re: Overlapping Shell Elements?
                  Seckin Uslu

                  edge contact can be acceptable. bonded contact type can be used for welded contact types.

                   

                  Make mesh refinement for convegrance

                  • Re: Overlapping Shell Elements?
                    Attilio Colangelo

                    I took a quick look at the model.  You need to have the surfaces coincident in the model geometry.  This will let you bond/weld/etc them together.  Account for the neutral axis offsets in the study shell definition (although it may not have much impact on results).

                    • Re: Overlapping Shell Elements?
                      Attilio Colangelo

                      Here's a screenshot of the shell model rendered as solids for visualization/checking shell offsets.  It takes some trial and error to get the "zero thickness" surfaces to properly represent the physical steel.  For instance, toggling the shell offset options will erroneously put the angle below the plate.

                       

                      Also, I did not delete any bodies in the geometry but rather chose to "not include in analysis" in the study options for those bodies.

                       

                      ShellTestModel.JPG

                      • Re: Overlapping Shell Elements?
                        Jared Conway

                        i think the issue here is your expectations from an automatic bonding perspective and compatibility between element types when bonding

                         

                        this will just take some trial and error but most should be documented well in the help, kb and training

                         

                        when in doubt if you really care about the interface, I would generally recommend solids